1 Scope
This document specifies a mechanism for exchanging data and messages in the following
cases:
-
a) exchange between a traffic management centre and ITS roadside equipment for traffic
management;
-
b) exchange between ITS roadside equipment used for traffic management.
This document is not applicable to:
-
— communication between traffic management centres and in-vehicle units;
-
— communication between ITS roadside equipment and in-vehicle units;
-
— in-vehicle communication;
-
— in-cabinet communication;
-
— motion video transmission from a camera or recorded media.
This document is suitable for use when both of the following conditions apply:
-
1) The data to be exchanged can be defined as one or more elements that can be retrieved
or stored – SNMP can support a wide variety of devices and has adopted the concept
of a management information base (MIB), which identifies the configuration, control
and monitoring parameters for ITS roadside equipment. This standardized approach is
commonly used for network management applications for devices such as routers, switches,
bridges and firewalls. It is also used in many regions to control devices such as
dynamic message signs.
-
2) Guaranteed, deterministic, real-time exchange of data is not critical – SNMP operations
typically require less than 100 ms, but the underlying network can cause multi-second
delays in delivering messages or even lost messages; thus, SNMP is not intended for
applications that require reliable sub-second communications.
This document can be used for:
-
— intermittent exchange of any defined data (normal SNMP operations allow messages to
be structured by combining any group of elements into a retrieval or storage request);
-
— repeated, frequent exchanges of the same message structure (with potentially different
values), even on relatively low-bandwidth links;
NOTE 1 The dynamic object feature, defined in ISO/TS 26048‑1, can be used to eliminate a considerable amount of overhead that is normally associated
with SNMP communications to make it more suitable for low-bandwidth links.
-
— allowing ITS roadside equipment to issue exception reports when special conditions
arise.
NOTE 2 Exception reporting uses SNMP notifications in combination with the notification management
features defined in ISO/TS 26048‑1.